I checked your account, and noticed that you have a free service account. You had already logged on for over 100 times. Please note the free FTP service is designed for personal and casual use only. You cannot use it too heavily. (you can only log on for certain numbers / day).

If you use automatic software / device that keeps connecting to our FTP server, you must order our paid subscription. Our paid service starts at only $1.99/month, or $19.99/year.

Seeing this post, I got the same error today, so I just order the basic plan a few minutes ago. I'm still getting the same error now, how long it take for paid subscription to be active for FTP access ...